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Blood Test May Help Confirm Parkinson's Diagnosis

Parkinson's disease (PD) is a complex and varied disorder with many different potential motor and non-motor symptoms. Early on, it can sometimes be difficult to determine whether symptoms are caused by Parkinson's or an atypical parkinsonism, a condition that shares some of the motor symptoms (tremor, slowness, stiffness) with PD. No single blood or imaging test exists to diagnose or differentiate these diseases. Early diagnosis is important because the treatment and progression of atypical parkinsonisms differs from that of Parkinson's.

A new study, published in Neurology, suggests that evaluating levels of a certain protein in the blood may help distinguish Parkinson's from certain atypical parkinsonisms (corticobasal degeneration, multiple system atrophy and progressive supranuclear palsy). Researchers found that amounts of a nerve protein called neurofilament light chain (NfL) was higher in people with atypical parkinsonism as compared to people with Parkinson's disease or those without either condition. While these results are promising, the researchers caution the test isn't ready to be used clinically to diagnose Parkinson's and that it can't tell the difference between the atypical parkinsonisms. The next step is to confirm the test results by studying them in larger numbers of people.

Identification of an objective measurement -- or biomarker -- for Parkinson's, such as the protein in this study, would allow for earlier diagnosis, better tracking of disease progression and more efficient testing of new therapies. Researchers are working to develop reliable standardized tests of NfL and deploy them in The Parkinson's Progression Markers Initiative (PPMI), The Michael J. Fox Foundation's landmark observational study looking to validate PD biomarkers. Work on NfL is anticipated to begin this year.